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Date and Time of the Query: 2019-06-18 T21:52:44 PDT
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For refcode 2005A&A...442L..39H:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2005A&A...442L..39H Spitzer IRS spectroscopy of 3CR radio galaxies and quasars: testing the unified schemes M. Haas, R. Siebenmorgen, B. Schulz, E. Krugel and R. Chini Received 18 July 2005 / Accepted 11 September 2005 With the Spitzer Space Telescope Infrared Spectrograph (IRS) we have observed seven powerful FR 2 radio galaxies and seven quasars. Both samples, the galaxies and the quasars, are comparable in isotropic 178 MHz luminosity (10^26.5^ W/Hz ~< P_178_,MHz ~< 10^29.5^ W/Hz) and in redshift range (0.05 ~< z ~< 1.5). We find for both samples similar distributions in the luminosity ratios of high- to low-excitation lines ([NeV]_14.3_ ~ {mu} m / [NeII]_12.8_ ~ {mu} m) and of high-excitation line to radio power ([NeV]_24.3_ ~ {mu} m / P_178_,MHz). This solves the long debate about the apparent difference of quasars and radio galaxies in favor of the orientation-dependent unified schemes. Furthermore, the luminosity ratio [OIII]_500.7_ ~ nm / [OIV]_25.9_ ~ {mu} m of most galaxies is by a factor of ten lower than that of the quasars. This suggests that the optical emission from the central NLR is essentially absorbed (A_V_ >~ 3) in the powerful FR 2 galaxies and that the [OIII]_500.7_ ~ nm luminosity does not serve as isotropic tracer for testing the unified schemes. Key words: galaxies: active, galaxies: nuclei, galaxies: quasars: general, infrared: galaxies
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